NBN Co has signed up 27 retailers to its wholesale broadband agreement (WBA), following the acceptance of the company's overarching regulatory, product, and pricing undertaking late last year.

Until now, retailers such as Telstra and Optus that have customers on the National Broadband Network (NBN) have operated on the network under a temporary agreement that was put in place while NBN Co, the industry, and the Australian Competition and Consumer Commission (ACCC) worked on finalising the overarching 30-year regulatory, product, and pricing document known as the Special Access Undertaking (SAU).

The ACCC finally accepted the document in mid December, allowing NBN Co to begin signing up the retailers to the WBA, which falls within the SAU, and lasts one year.

NBN Co announced this morning that 27 wholesale customers, including Telstra and Optus, have signed onto the new WBA, which will be in place by March this year.

"Significant progress has been made in the development and execution of NBN Co's new supply arrangements, and NBN Co thanks customers for their engagement in relation to the new WBA," NBN Co's head of Regulatory Affairs and Industry Analysis Caroline Lovell said in a statement.

NBN Co said it would look to continue to refine the agreement, and adapt it as required.